There is no need to change templates.
In Ground Forces - Order of Battle you have list of your ground formations.
For example I have two geosurvey formations. When I select Show Elements button (upper left part) I can see that each has 4 vehicles. I can transfer those vehicles from one formation to the other by dragging vehicles from one formation and dropping them into the other formation.
If you select Amout Popup button (upper left part) before dragging then you can decide how many vehicles to transfer.